1. FACET Accelerator Overview
John Seeman for the FACET Study Group
PPA Directorate
Stanford Linear Accelerator Center
DOE FACET Review
February 19-20, 2008

2. Topics FACET accelerator overview Brief look at science program
Changes since the SABER review of Dec 2006
Brief budget overview

3. FACET Accelerator Team
Management: R. Erickson, S. Kahn, J. Jaros, D. MacFarlane, T. Raubenheimer, J. Seeman
Mechanical engineers: L. Bentson, D. Blankenship, S. DeBarger, N. Li, H. Shin
Area Manager: A. Baker, T. Graul
Optics: Y. Nosochkov, M. Woodley, T. Fieguth
Alignment: C. LeCocq
Beam dynamics: K. Bane, P. Emma
Radiation physics: J. Bauer, A. Prinz
Personnel Protection System: P. Bong, K. Turner
Experimental region: M. Hogan, D. Walz, M. Woods, C. Hast
Physics consultants: R. Iverson, P. Krejcik

4. Overview
There was a constant demand for electron and positron beams in the Final Focus Test beam (FFTB) and End Station A (ESA) from a wide variety of accelerator physics users.
However, the FFTB has been removed to make room for the Linac Coherent Light Source (LCLS). ESA is still in use.
Many locations at SLAC have been studied for FACET. The optimum location is Linac Sector 20 for the Accelerator Science Facility (ASF) where the FFTB accelerator beam capabilities (final focus) can be relocated in a straight forward fashion.
FACET makes use of the PEP-II HER bypass line to take a damped e- beam to End Station A, independent of LCLS.
The existing electron longitudinal bunch compressor at the 1/3 point in the linac can be modified to compress positron bunches, as well, opening new worldwide unique opportunities for accelerator research.
A Hadron Production Facility (for single particles) can be added to the A-Line to ESA.

5. FACET Layout FACET has four areas:
Hadron Production Facility
FACET has four areas:
Accelerator Science Facility (ASF) (Sector 20)
e+ bunch compressor (Sector 10)
Electron Bypass Line (EBL) extension to ESA
Hadron Production Facility in A-Line to ESA

6. Basic FACET areas
Final Focus (ASF) in Sector 20: Makes a small beam spot (<10 microns) for experimenters. Similar design and layout as FFTB final focus.
Sector 10 compressor for e+: Allows the production of positrons by e- and the delivery of short bunch length e+ to the experimenter. Same design and layout as present e- compressor.
Bypass line (EBL): Allows independent operation from LCLS. Use PEP-II HER injection bypass lines with 9 to 12 GeV e- with extension built to join to A-line transport to ESA.
 The technology is the same as the former FFTB, SLC arcs, and existing PEP-II injection bypass lines. Many components salvaged from SLC, FFTB, and PEP-II.
 Minimal design and engineering needed!

7. Proposed Construction Timeline
Fall 2008: Installation of shielding wall in linac tunnel between Sectors 20 and 21. This allows tunnel installation work to proceed in Sector 20 while the LCLS injector and other downstream systems operate in 2009.
January through September 2009: Installation of Sector 20 magnets and vacuum systems while LCLS commissioning activities proceed in downstream sectors.
Fall 2009: Removal of existing components of the PEP-II injection transport systems in the BSY, as needed for FACET EBL. Modifications will be done to the common line vacuum system in the BSY.
FY 2010: First operation of Sector 20 ASF final focus with electrons. Installation of positron compressor system in Sector 10.
Fall 2010: Installation of the bypass line in the BSY and Hadron Production Facility.
FY 2011: All FACET systems fully operational, independent of LCLS operations.

8. Basic FACET ASF Beam Parameters
Beam Energy = 30 GeV
Single bunch per pulse
30 Hz (120 Hz possible)
Charge per bunch (e- or e+) = 1 x 109 to 3.5 x 1010
Bunch length = microns
Transverse spot size at experiment <10 microns
Energy spread = 0.5 to 4 % (full width)

9. Sector 20 Final Focus

10. FACET Sector 20 Area e-
e+ target

11. LCLS Injector (Sector 21)
New FACET Wall

12. Linac Housing: Site of ASF

13. Linac Tunnel
ASF has a bunch compression dog-leg beam line and a final focus for the experiment.
Longitudinal space for experiments will be the same as the FFTB.
Transverse space is adequate for accelerator experiments and many detector experiments.
Electric carts can travel in the linac tunnel aisle now and will be able to after the ASF and experiments are installed.

14. Many places for User Counting Houses

15. Basic FACET EBL-ESA Beam Parameters
Beam Energy = 9-12 GeV using PEP-II HER line
Single bunch per pulse
30 Hz (120 Hz possible)
Charge per bunch = 1 x 109 to 3.5 x 1010
Bunch length = ~1 mm
Transverse spot size at experiment < 1mm
Energy spread = <1 %

16. Extension of HER Line to A-Line

17. Plasma Wakefield Acceleration Studies (ASF)
Electron acceleration
Positron acceleration
Drive witness beam tests
Beam emittance preservation

18. Dielectric Wakefield Accelerators (ASF)
Acceleration (e- and e+)
CSR studies
Coating optimization
Beam propagation tests
Theory/simulation cross checks
Channel diameter optimization

19. Detector Development (ESA)
Development of beamline instrumentation for ILC or other applications
New position monitors
Precise beam energy measurements
Collimator wakefield studies
Detector development for ILC, LHC and many other applications
Proof-of-principle for new detectors
Detector characterization and calibration
EMI & radiation damage studies
Gas/air fluorescence for particle astrophysics experiments

20. Material Science (ASF and ESA)
Pulsed magnetic fields
THz radiation
Photon detector development
Electronic structure of metals
Ferroelectric switching

21. Old Proposal: SLAC Overview with SABER in SLC South Arc
SABER consists of three main components:
(1) Experimental area with final focus and beam dump in SLC South Arc tunnel.
(2) Linac Pulse Compressor upgrade to compress positron bunches.
(3) Bypass Line to deliver e- or e+ beams to SABER, bypassing the LCLS.
(2) e+ e-
(3)
(1)

22. Old SABER: Reuse 1 km of PEP-II Injection Bypass Line
Sector 20 (exists)
Linac Sector (exists)
51 Line (exists)
South Arc
(exists)
Extraction
Line (new)
Re-injection
Line (new)
Drift Line
(exists but 12  30 GeV)
~50 m
~1000 m
~50 m
Drift Line:
Reuse: Vacuum chambers, pumps and controls
Beam position monitors
Beam size monitors
Steering corrector magnets
Quadrupole magnets and power supplies
New: Extra quadrupole magnets, power supplies, supports, water

23. Suggestions from SABER Review
FACET team has answered the committee recommendations from the DOE “SABER” review held December 6-7, 2006:
Broader science program:
Added ESA beam for detector and accelerator studies.
Added hadron production facility for single particle detector studies.
New location and lowest cost:
Final focus in Sector 20 saves bypass line upgrade costs and has easier beam tuning. (Saves 3.6 M$)
ASF and ESA can operate simultaneously, independent of LCLS.
Manage the construction as a project:
Project management team is now proposed.

24. Budget changes from SABER  FACET (FY2007$)
SABER budget total: 12.4 M$
South Arc final focus: 2.4 M$
Linac bypass line (30 GeV) upgrade: 8.3 M$
Positron Bunch Compressor: 1.5 M$
Personnel Protection System upgrade: 0.2 M$
FACET budget total: 15.5 M$
Sector 20 ASF final focus: 7.1 M$
Positron bunch compressor: 1.5 M$
EBL Bypass line extension to ESA (12 GeV): 4.3 M$
ESA Hadron Production Facility: 0.6 M$
Project management: 2.0 M$
Operations costs: ~6 M$ for 4 months for running both ASF and ESA together.

25. Conclusions
FACET (ASF and ESA) is a solid advance over the old design.
The breath of the experimental program has been significantly expanded.
There are four components to the facility allowing staging of the program.
FACET construction matches the LCLS staff ramp down plan and accelerator operations schedule.
Budget estimates have been carefully managed to be as low as possible.